Methods to optimize selective hyperthermia

Thomas M. Cowan; Christopher A. Bailey; Hong Liu; Wei R. Chen

doi:10.1117/12.473750

27 August 2003 Methods to optimize selective hyperthermia

Thomas M. Cowan, Christopher A. Bailey, Hong Liu, Wei R. Chen

Proceedings Volume 4961, Laser-Tissue Interaction XIV; (2003) https://doi.org/10.1117/12.473750
Event: Biomedical Optics, 2003, San Jose, CA, United States

Abstract

Laser immunotherapy, a novel therapy for breast cancer, utilizes selective photothermal interaction to raise the temperature of tumor tissue above the cell damage threshold. Photothermal interaction is achieved with intratumoral injection of a laser absorbing dye followed by non-invasive laser irradiation. When tumor heating is used in combination with immunoadjuvant to stimulate an immune response, anti-tumor immunity can be achieved. In our study, gelatin phantom simulations were used to optimize therapy parameters such as laser power, laser beam radius, and dye concentration to achieve maximum heating of target tissue with the minimum heating of non-targeted tissue. An 805-nm diode laser and indocyanine green (ICG) were used to achieve selective photothermal interactions in a gelatin phantom. Spherical gelatin phantoms containing ICG were used to simulate the absorption-enhanced target tumors, which were embedded inside gelatin without ICG to simulate surrounding non-targeted tissue. Different laser powers and dye concentrations were used to treat the gelatin phantoms. The temperature distributions in the phantoms were measured, and the data were used to determine the optimal parameters used in selective hyperthermia (laser power and dye concentration for this case). The method involves an optimization coefficient, which is proportional to the difference between temperatures measured in targeted and non-targeted gel. The coefficient is also normalized by the difference between the most heated region of the target gel and the least heated region. A positive optimization coefficient signifies a greater temperature increase in targeted gelatin when compared to non-targeted gelatin, and therefore, greater selectivity. Comparisons were made between the optimization coefficients for varying laser powers in order to demonstrate the effectinvess of this method in finding an optimal parameter set. Our experimental results support the proposed use of an optimization coefficient to find optimal parameters for selective hyperthermia.

Citation Download Citation

Thomas M. Cowan, Christopher A. Bailey, Hong Liu, and Wei R. Chen "Methods to optimize selective hyperthermia", Proc. SPIE 4961, Laser-Tissue Interaction XIV, (27 August 2003); https://doi.org/10.1117/12.473750

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